Abstract
During a 5-month field study on the primates of northern Bolivia, it was found that two callitrichid species, Saguinus fuscicollis and Saguinus labiatus, formed apparently stable mixed troops, sharing a common home range, and associating for approximately 50% of their day. The groups joined together each morning and sometimes stayed together for several hours, up until mid-afternoon. In some localities, a Callimico goeldii group was also present, and they shared the same home range and associated a great deal with the mixed Saguinus troop. The mechanisms by which these associations are established and maintained are discussed. Possible reasons for the high degree of polyspecific association are proposed. Other associations between the Saguinus species and larger primates are also described.